Automatic transmission and controls

ABSTRACT

Power transmission having torque converter drivingly connected to a planetary gear unit conditionable by selective engagement of friction drive establishing devices to provide for four forward drives and one reverse drive. A converter clutch normally held from engagement by the feed of fluid into the converter through a clutch control chamber can be engaged by converter pressure in response to an upshift signal and subsequent exhaust of fluid from the control chamber to permit mechanical drive of the gear unit. A shift valve forming part of hydraulic controls provides a signal pressure to open a converter feed restrictor valve to permit the converter to be fed with operating oil through a second feed passage. The signal from this valve also activates an accumulator valve system which controls the engagement of the converter clutch so that converter clutch capacity is gradually increased to a maximum. There is a detent valve which provides for 3-2 and 4-3 part throttle downshifts and 4-2, 3-2 and 2-1 full throttle downshifts.

D United States Patent 115] 3,638,77 1 Chana 1 Feb. 1, 1972 [541AUTOMATIC TRANSMISSION AND 3,541,893 11/1970 Dyke et al ..192/3.3 x

CONTROLS Primary Examiner-Allan D. l-lerrmann [72] Inventor: Hum! ChumAttorney-W. E. Finken, A. M. Heiter and Charles R. White [73] Assignee:General Motors Corporation, Detroit, 1

' Mich. [57] ABSTRACT [22] Filed: July 30, 1970 Power transmissionhaving torque converter drivingly connected to a planetary gear unitconditionable by selective en- [21] Appl' 59467 gagement of frictiondrive establishing devices to provide for Related Applicant. Data fourforward drives and one reverse drive. A converter clutch normally heldfrom engagement by the feed of flu1d into the Continuation-impart 0f389,779, converter through a clutch control chamber can be engaged 1969-by converter pressure in response to an upshift signal and subsequentexhaust of fluid from the control chamber to permit [52] US. Cl..192/3.33, 74/645, 74/869, mechanical drive f the unit' A hift valve fi part f 192/352 hydraulic controls provides a signal pressure to open acong gf i 67/00 Fozd 860k 17/02 verter feed restrictor valve to permitthe converter to be fed l do 5 g with operating oil through a secondfeed passage. The signal I from this valve also activates an accumulatorvalve system which controls the engagement of the converter clutch sothat [56] Reerem Cited converter clutch capacity is gradually increasedto a max- UNITED STATES PATENTS imum. There is a detent valve whichprovides for 3-2 and 4-3 part throttle downshifts and 4-2, 3-2 and 2-1full throttle 3,001,415 9/1961 Smrrl ..74/645 X d w hift 3,463,0338/1969 Fisher ..192/3.26 X 3,465,856 9/1969 Biabaud ..l92/3.33 12Claims, S'Drawlng Figures 16 0 //I x as 962 w 92 1! f W *F & a; 20 '1'87 if 15? x. N

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sum 3 or 3 GOVERNOR BY Howard 6. Cfiazza 11 (KM/w ATTORNEY AUTOMATICTRANSMISSION AND CONTROLS This application is a continuous-in-part of myearlier application, Ser. No. 880,779, filed Nov. 28, 1969.

This invention relates to automatic transmissions and controls whichprovide for automatic all hydraulic, split torque or all mechanicaldrive. More particularly, this invention relates to advanced hydrauliccontrols for the transmission gearing and for the control of a frontclutch using converter pressure.

Automatic transmissions with a large number of gear ratios have employeda front clutch for mechanical drive of planetary gearing to produce anoverdrive ratio and to cooperate with torque converter drive of thegearing to produce split torque drives. The gearing, clutches and brakesand hydraulic controls comprising such transmissions have generally beenhighly complex, expensive and therefore impractical for mass productionand have not had wide-spread usage. In may cases a special planetarygear unit had to be employed for anoverdrive ratio greatly adding to thetransmission weight and complexity. This invention provides for new andimproved torque converter, converter clutch, planetary gear unit andcontrols to produce all hydraulic low and intermediate drives, a splittorque l:l drive and an all mechanical overdrive. This inventionutilizes only simple planetary gearsets, a minimum number of frictiondrive establishing devices and uncomplicated controls providing a highlysuitable transmission for quantity production. The converter clutch isengaged by the force of converter pressure to provide for mechanicaldrive into the planetary gear unit to improve efficiency of transmissionoperation for vehicle cruising. The controls include 1-2, 2-3 and 3-4shift valves which respond to torque demand and vehicle speed signals byupshifting and downshifting for automatic operation of the transmission.Operating oil is fed to the converter from the 2-3 shift valve whendownshifted through a control chamber for the front clutch to effectrelease of the front clutch so that first and second range drives areall converter drives. When upshifted, the 2-3 shift valve provides asignal that opens a restrictor valve so that fluid is fed to theconverter through a second feed passage. An accumulator valve systemcontrols the engagement of the converter clutch to provide improvedshifting into direct drive. After the 2-3 shift v'alve signals anupshift, the control fluid from the clutch chamber is graduallyexhausted so that the clutch capacity gradually increases to a maximumwhen the accumulator has obtained its maximum capacity. The controlsinclude a detent valve which modifies the shift schedule of thetransmission and provides for 3-2 and 4-3 part-throttle downshifts and4-2, 3-2 and 2-1 wide-open-throttle downshifts. Low, intermediate andreverse drives may be manually selected by moving the manual valve topredetermined positions to set the automatic controls for theserespective operations.

These and other features, advantages and objects of the invention willbecome more apparent from the following detailed description anddrawings in which:

FIG. 1 is a longitudinal sectional view of a portion of thetransmission.

FIG. 2 is a chart which illustrates operation of the converter clutch ofthis transmission.

FIG. 3 is a diagram showing how FIGS. 4a and 4b are to be placed toillustrate a complete transmission control.

FIG. 4a is a diagrammatic view of a first part of the transmissioncontrol of this invention.

FIG. 4b is a diagrammatic view of a second part of the transmissioncontrol of this invention.

As shown in FIG. 1 this transmission has an input which is drivinglyconnected to the front cover of a housing 12 of a hydrodynamic torqueconverter 14. The torque converter has a bladed pump 16 operativelyconnected to housing 12 and has a bladed turbine 18 and stator 20. Thestator is connected through a one-way brake 22 to a ground sleeve 24.The turbine 18 is drivingly connected to the flange of a hub 26 which issplined to a sleeve shaft 28. Sleeve shaft 28 extends rearwardly in thetransmission and is splined to the inner hub of an annular drum 30. Thisdrum houses the friction plates of a forward drive clutch 32 havingdrive plates splined to the interior wall of the drum and having drivenplates, disposed between the drive plates, splined to the outerperiphery of annular plate support hub 34. The support hub is splined toan intermediate sleeve shaft 36 which drives a first planetary gearset38.

An annular piston 40 is housed in drum 30 and cooperates therewith toform clutch apply chambers 41 and 42 connected by restricted passage 43.When working fluid under pressure is supplied to chambers 41 and 42through forward clutch line 46, the piston will move axially to effectengagement of forward clutch 32. By virtue of the restricted passage 43,chamber 41 gradually fills with this fluid to increase clutch capacity.This dual capacity clutch construction provides for softer and bettertimed shifts particularly a 4-3 downshift when the chambers areexhausted. Spring 44 is a-return spring supported in drum 30 forengaging and moving the piston from engagement with clutch 32 when thepressure fluid in the apply chambers is exhausted.

The intermediate shaft 36 is splined to the sun gear 48 of the firstplanetary gearset 38. This gearset has elongated planet gears 49 whichmesh with the sun gear 48 and also with a ring gear 50 which has aninner hub portion splined to the end of a drive shaft 51. This driveshaft extends longitudinally in the transmission and has its forward endsplined to a front annular hub 52. This hub has an annular shoulder 53that slidably supports a disklike plate 54 having an outer annularfriction member that is engageable and disengageable with a frictionsurface on the inside of the front cover of the converter housing 12 toprovide a front clutch 55. The plate 54 carries a series of rearwardlyprojecting fingers 56 that extend into openings formed in a radialflange 57 of the hub 52 to drivingly connect the friction plate and thehub and the drive shaft 51. Tickle spring 58 trapped between the flange57 and the friction plate 54 urges the friction plate forwardly so thatthe clutch has a positive engagement bias at all times. The frictionplate 54 and the front cover of the converter housing form a chamber 59which is connected by a passage 60 to a converter clutch line 61.Operating fluid when supplied to the converter through line 61, passage60 and chamber 59 effects disengagement of clutch 55 while feeding theconverter.

The planetary gearset 38 has a carrier 62 which fixedly supports pivotpins 63 on which planet gears 49 are rotatably mounted. The planetarycarrier is rigidly secured to the interior of an output shell 65 whichis splined to a rearwardly extending output shaft 64. Also, thisplanetary gearset has a second ring gear 66 meshing with planet gears 49which has a forwardly extending portion that surrounds a secondplanetary gearset 68 disposed adjacent to the planetary gearset 38.

Planetary gearset 68 has a sun gear 70 which meshes with the planetgears 72 that in turn mesh with the ring gear 74. Ring gear 74 extendsrearwardly and is connected to the carrier 62 of the first gearset whilethe carrier 76 of planet gears 72 of the second gearset is rigidlysecured to the interior of the extension of ring gear 66.

A multiplate low and reverse friction brake 78, disposed between ringgear 66 and the interior of transmission housing 80, is engageable by ahydraulically operated piston 82 to connect the ring gear to the housingto establish low and reverse drive ratios as will be further explainedbelow. This piston is movably mounted in the rear of the transmissionhousing and cooperates therewith to form separate pressure chambers 84and 86 connected to low and reverse line and reverse line 87respectively of the transmission controls. For manual low speed drives,chamber 84 is supplied with pressurized working fluid to effect themovement of piston 82 and the engagement of brake 78. For reverse,higher reaction torques are needed and the torque capacity of brake 78is increased by charging both chambers with working fluid. Returnsprings 88 secured to housing 80 move the piston to the off positionwhen the apply chambers are exhausted.

Disposed adjacent to multiplate brake 78 is a one-way brake 90operatively connected to the outer periphery of ring gear 66 and theinterior of the transmission housing. This brake automatically engagesto prevent the reverse rotation of the ring gear 66 and the carrier 76and automatically disengages to allow these elements to rotateforwardly.

The sun gear 70 of the second planetary gearset has a forwardlyextending sleeve portion concentric with sleeve shaft 36 and this sleeveportion is connected to a sheet metal drum 92 that extends forwardlyaround drum 30. As shown, drum 92 has extending tabs or projectionswhich fit in special openings formed in an annular flange portion of adrum 94 which is rotatably mounted on an inner-extending shoulderportion 95 of the transmission housing. The drum houses a piston 97which forms pressure chambers 98 and 99 within the drum 94 connected bypassages 100 and 101 to reverse passage 109 and reverse clutch line 107respectively.Apply oil when fed by the controls to chamber 99 or bothchambers 98 and 99, causes the piston to engage a multiplate reversedrive clutch 102. This clutch has driven plates splined to the interiorof drum 94 and drive plates interleaved with the driven plates andsplined to an annular shoulder extending forwardly from drum 30. Theengagement of clutch 102 connects drums 94 and 30 together. Returnsprings 104 secured to drum 94 engage the piston 97 to move it to an offposition when chambers 98 and 99 are exhausted. Conventional ball dumpvalves such as valve 105 are employed in this transmission. This valveopens to exhaust chamber 98 when the drum 94 is rotating to preventresidual centrifugal oil from effecting movement of piston 97 andengagement of clutch 102. There is an annular brake band 103 which isoperated by a servomechanism for selectively engaging drum 94 to hold itfrom rotation when establishing predetermined ratios.

Mounted on a forwardly extending collar portion of drum 94 is the innerrace of a one-way clutch 106. There is also a multiplate intermediatebrake 108 having a first series of plates splined to the outer raceof'this one-way device and a second series of plates splined to theinterior of housing 80. Piston 110 slidably mounted on an interiorshoulder of transmission housing 80 engages the brake 108 when thepressure chamber 112 formed by this piston and the housing is chargedwith apply pressure through intermediate clutch line 114. Suitablereturn spring means supported on the transmission case are employed tomove piston 110 to an inactive or off position when the associated applychamber is exhausted.

Instead of being supplied with working fluid through passage 60 theconverter 14 may also be supplied with working fluid through feed line118 and passage 120. In both cases converter discharge is throughpassage 122 into converter out passage 124.

With the invention as shown and described a plurality of forward driveratios, a neutral and a reverse drive ratio can be readily obtained. Theschedule of engagement of the clutches and brakes to obtain these ratiosis set forth in the following chart:

32 as shown in the schedule. Under these conditions the outer race ofone-way clutch 106 is grounded and this one-way device locks to hold sungear 70 for reaction. With ring gear 74 rotating forwardly and with sungear 70 held, the planet gears 72 will be driven forwardly. The outputspeed of ring gear 74 and connected output shaft 64 increase as theplanet gears walk on the stationary sun gear 70 to produce anintermediate speed ratio. During this drive the one-way brake 90overruns. For a preferred split torque direct drive indicated as drive3, the front clutch 55 and forward clutch 32 are applied.

5 Under these conditions sun gear 48 will be driven by the converter andring gear will be driven mechanically to produce a ratio of 1:1. Thisdrive will be two-thirds mechanical and one-third hydraulic. Theintermediate brake 108 is on but has no effect on this drive since theone-way clutch 106 overruns.

For a torque converter direct or third range drive, clutches 102 and 32are applied as indicated by optional drive 3A. Under these conditionsthe sun gears 70 and 48 are connected and the planetary gearset islocked up for rotation as a unit in a ratio of 1:1. Intermediate brake108 is on but has no effect on this operation since the one-way clutch106 overruns.

If an all mechanical direct drive is desired the front clutch isadditionally engaged as indicated in optional drive 38. With the gearsetlocked and driven mechanically through the clutch 55 there is noconverter slippage and operating efficiency is improved.

For overdrive, front clutch 55 and brake band 103 are engaged. With sungear held for reaction and ring gear 50 mechanically driven forwardly,an all mechanical overdrive is produced with the carrier 62 and outputshaft rotating faster than input 10.

For low hold, forward clutch 32 and brake 78 are applied. With sun gear48 driven forwardly by the converter and ring gear 66 held for reactionthe carrier 62 and connected output shaft will be driven forwardly atthe low speed ratio. Since brake 78 is engaged the ring gear 66 is heldfrom rotation so that it cannot overrun the one-way brake to preventfree wheeling under coast conditions for engine braking. As shown in theschedule, one-way brake 90 is on to assist in holding the 45 ring gearfrom reverse rotation.

For intermediate hold, forward clutch 32 is engaged to transmitconverter torque to sun gear 48 and brake band 103 is engaged with drum94 to hold sun gear 70 for reaction. Under these conditions the twocarriers 62 and 76 compound 50 so that forward rotation of sun gear 48results in forwardmedium speed drive of the carrier 62 and the connectedout- The application of brake band 103 prevents Friction elementsExample 103 106 90 Converter ratio On L0ek.. Leek Open 2.87/1

2 n.... On ..do.. ...do 1. 64/1 3 0n On.... On Or.... Or.... Splittorque. 1/1

3A (optiong- On.... On.... On. Or- Or---. Open 1/1 3B (option On On On.Or Or. Locked 4 On. Or ...do. Low Lock Lee Open. Intermediate. On....On. 0n.. ...do.. Or... ...-do. Reverse 0n On ..do-

When the transmission is set for automatic drive, first.

second, third and fourth speed ratios are automatically selected inaccordance with torque demand and vehicle speed signals. When torquerequirements are high as when initially moving the vehicle, forwardclutch 32 is applied. Turbine torque is transmitted by clutch 32 throughsleeve shaft 36 to the sun gear 48 of the planetary gearset 38. Ringgear 66 will be held by the one-way brake 90 and the carrier 62 will bedriven forwardly at low speed in the largest reduction ratios such aslisted in the schedule. The one-way clutch 106 locks b this 5 5. 9 3.st??? st rs si s? b55591"? i e e s? at 65 freewheeling of the one-waydevice 106 under predetermined 66 and 50 have 86 teeth each to producethe example gear ratios listed above. Other beneficial ratios can bereadily produced by appropriately changing the teeth numbers of thegearing components.

The hydraulic controls of this invention include an intemalexternalgear-type pump 130 disposed immediately behind the torque converter pumpwithin a pump housing 134 disposed in the transmission housing 80. Theexternal gear of the pump is keyed to a sleeve 136 of the converter pump16 so that the pump pumps transmission oil whenever the engine isoperatmg.

As shown schematically in FIGS. 4a and 4b the pump has an intakeconnected to suction line 138 which is connected to an oil strainerassembly and sump 140. Oil is delivered by the pump into main line 142.Oil pressure in the control system is controlled by a pressure regulatorvalve 144 which is spring balanced to regulate line pressure at apredetermined value. The regulator valve has a main valve element 146, amodulator trim and reverse boost element 148 forming a boost chamber 149connected to reverse line 87, and a pressure boost plug 150. Minimumregulated line pressure is controlled by a centrally disposed spring 152which is seated in the bore of valve 144 and which has a free endengaging the end of the main valve element 146. Main line pressure isfed to a chamber 153 located in one end of the regulator valve to exerta force on the main valve element 146 which opposes the force exerted bythe spring 152. As the pressure builds up in the chamber 153, the mainvalve element 146 moves down against the spring 152 to reduce linepressure by exhausting pressure fluid to suction line 155 connected tothe sump 140. The movement of this valve element opens converter feedport 158 and connected converter feed line 118 to a main pressure port160 connected to the main line 142. The converter feed line 118 isconnected to a converter blow-off valve 161 and also into the passage120 through a converter feed restrictor valve 162. If main line pressurecontinues to increase in chamber 153, the valve element will openpressure port 160 to an exhaust port 164 connected to the suction line155 leading into sump 140. If the pressure in the main line drops, thespring 152 will move the main valve element 146 into a position blockingmain line pressure portl60 from the exhaust port 164 to effect a mainline pressure rise. To provide for increased regulated pressure, themodulator trim and reverse boost valve element can be moved to exert aforce on the main regulator valve tending to close main line pressureport 160 from exhaust port 164 regardless of line pressure. This occurswhen there is a supply of a reverse pressure through reverse line 87 toact on the differential area of the lands of the boost element 148.Also, pressure from a modulator trim valve which will be laterdescribed, can be supplied to a pressure chamber 165 formed betweenboost element 148 and plug 150. When this chamber is charged withpressure oil, an additional force is exerted on the main valve element146 to increase main line pressure. The regulated pressure can also beincreased by supply of a boost pressure to chamber 170 behind boost plug150 through boost line 172. The force exerted by this boost pressureurges the plug 150 and valve element 148 against the end of the mainregulator valve element 146 moving it toward the illustrated position.In this position the suction line 155 is blocked from pressure port 160and the main line pressure is thereby increased.

Regulated main line pressure is routed through line 142 into a port 176of a manual valve 178 which has a valve element 180 axially shiftable bya manual selector lever or other selector mechanism. The manual valveelement is movable to the illustrated position L L,, D, N, R, P whichcorrespond to low, intermediate, drive, neutral, reverse and park,respectively.

in the the L or low range position the manual valve element 180 connectsmain line pressure to a low control line 182, a drive line 184 and anintermediate line 186. In the L or intermediate position of the manualvalve element, main line pressure is connected to the drive andintermediate lines. The low pressure line is exhausted through passage187 in the manual valve element and exhaust ports 188. in the driveposition D the manual valve element is shifted to a position in whichmain line pressure is connected to a reverse-neutral-drive or RND- line192 and to drive line 184. The intermediate and low lines are exhaustedthrough passage 187 and exhausts 188. ln the neutral position the mainline pressure port 176 is connected to the RND-line 192 and all of theother lines connected into the manual valve are exhausted. ln reverseposition the main line pressure is connected to a reverse port 194connected to reverse line and the RND-line 192 and the other lines areopened to exhausts188. in part, the main line pressure port 176 isblocked by the shifted manual valve element and all other lines areexhausted.

Vehicle speed signal for automatic shifting is supplied by a suitabletransmission governor 198 such as the governor shown in Pat.application, Ser. No. 811,439 to Henri J. Van Lent et al., filed Mar.28, 1969, now U.S. Pat. No. 3,541,887 which is driven by thetransmission output shaft 64. The governor is fed with drive oil fromthe manual valve through line 184 and provides a governor pressure intogovernor line 200.

To provide a variable engine torque signal the controls include amodulator valve 204 in which a modulator valve element 206 operating asa simple regulating valve converts modulator force into a hydraulicmodulator pressure. 'This valve has inlet port 208 connected to mainline 142, a modulator outlet port connected to modulator line 210 andhas an exhaust 211. An engine torque signal is exerted on one end of themodulator valve element 206 by a suitable vacuum modulator such as thatdisclosed in the above-identified U.S. application, Ser. No. 81 1,439 toHenri J. Van Lent et al.

Modulator pressure is fed into end chamber 212 of the modulator valvethrough a suitable passage 213 in the modulator valve element to exert aforce opposing that of the vacuum modulator. The modulator force andthus modulator pressure increase with increased engine manifoldpressure. Modulator pressure is supplied through the modulator line 210to an end chamber 215 in a modulator trim valve 214 and to a chamber 217in a 3-4 shift valve 216.

The modulator trim valve produces a pressure fed to a modulator trimline 218 which is directly proportional to modulator pressure andinversely proportional to governor pressure. This valve has an inletport connected to main line 142 and a shiftable valve element 220.Governor pressure is fed by governor line 200 to a chamber 222 at oneend of the valve element which opposes the force of modulator pressurein chamber 215 effective at the other end of the valve. When modulatorpressure is sufficiently high, valve 220 moves to open the inlet or lineport to the modulator trim line 218.

Modulator trim pressure is fed by line 218 to the pressure chamber 165between boost plug and boost valve element 148 in the pressure regulatorvalve to urge modulator trim and boost valve element to the rightagainst the regulating valve element to effect an increase in linepressure. Also the modulator trim line is connected to an inlet port 225of a detent valve 226.

The detent valve controls or modifies the shift schedule of thetransmission in accordance with engine torque as reflected by throttlecontrol position. With this valve, 3-2' part throttle downshifts, 4-3part throttle downshifts and wide-open throttle 4-2, 3-2 and 2-1downshifts are obtained to improve vehicle performance.

The detent valve has a valve element 228 which is operatively connectedto the throttle linkage, not shown, and is shiftable between thepredetermined positions shown as 0, 3-2, D and D in accordance withthrottle opening. Axial movement of the detent valve element 228 inresponse to the opening of the throttle is opposed by coil spring 230disposed in a spring pocket 232 having exhaust 233 at one end of thevalve element. This movement is also opposed by an outer spring 234trapped between a spring support secured to the yalve element and aspring seat 238 fixed to the valve housing. There is an inner coilspring 240disposed between the outer fixed support 236 and an innersupport or washer 242 normally seated against a shoulder on the valveelement. After predetermined movement of the valve element by thethrottle control, washer 242 contacts spring seat 238 and spring 240adds to the force opposing valve movement by the throttle pedal. As thevalve element 228 is moved from the D to the D position spring 240establishes a detent feel position to inform the operator that thetransmission will be conditioned for wide-open throttle downshifts onfurther opening of the throttle.

The detent valve also has: 1) a port connected to a detent- 2 line 246leading to the modulator trim valve 214 and into a l-2 shift valve and a2-3 shift valve later described, (2) a detent-1 port connected to adetent-l line 250 leading into the 3-4 shift valve 216, (3) an inletport 252 connected to the detent pressure regulator valve 254, (4) anoutlet port 256 connected to the modulator shift valve line 258, (5)part throttle port 260 connected to a 3-2 part throttle line 262 and (6)an exhaust 264.

In the 3-2 part throttle downshift position the 3-2 part throttle port260 is connected to the modulator trim inlet port 225. When the valveelement is moved further down to the D position, the D port is connectedto the detent regulator port 252 and the 3-2 part throttle port remainsconnected to the modulator trim inlet port 225. As the valve element 228moves to the D or wide-open throttle position the 3-2 part throttle port260 remains connected to the modulator trim port but the modulator shiftvalve port 256 becomes connected to the detent regulator port. The D,port, which previously was exhausted is also connected to the detentregulator port in this wide-open throttle position of the detent valveelement. There is a detent ball check valve 268 disposed between themodulator trim line 218 and detent-2 line 246 which blocks flow frommodulator trim line 218 to the detent-2 line; as indicated by the arrow,this valve allows flow from line 246 to line 218. This valve insuresthat in the D position of the detent valve element, modulator trimpressure can be greater than detent regulated pressure but cannot beless than this pressure.

The detent regulator valve 254 provides a regulated pressure for thedetent valve. This valve has a valve element 270 shiftable in a bore inthe valve housing. This valve has an inlet port 272 connected to mainline 142, a detent regulator port 274 connected to the detent regulatorline 276 and has an exhaust 278. There is an end chamber 280 which isconnected to the detent regulator line 276 and oil from that line is fedinto this chamber through a suitable flow control restriction. The forceexerted by detent regulator pressure on the valve element is opposed byspring 284 disposed in a spring pocket at the other end of the valve.

As shown in FIG. 4b, the controls include a low control valve 288 whichis governor pressure controlled and which limits the speed at which amanual low gear engagement can be made. Once this valve triggers manuallow engagement, the transmission will remain in first gear for as longas the pressure port for low control line 182 in the manual valve ispressurized. The valve 288 has a valve element 290 biased in onedirection by a spring 292 disposed in an end chamber 294 against theforce of governor pressure fed by governor line 200 to an end chamber296 in the valve. This valve includes an inlet port 298 connected to thelow range control line 182. Also low control valve 288 has a manual lowport 300 connected to a manual low line 302 that is connected to port304 of l-2 shift valve 306. Also the manual low line 302 is connected tothe chamber 294 to supply this chamber with pressure when the manualvalve is in the L position. Thus, in manual low a fluid pressure fed tochamber 294 exerts a force on the valve element 290 additive to theforce of spring 292.

The manual low control valve 288 is positioned to exhaust the manual lowline 302 when the manual valve is placed in the. manual low position andwhen the vehicle speed is more than a predetermined speed. At speedsbelow this, low range oil is fed by the low control valve into themanual low line 302.

This pressure oil is fed into a chamber 308 in the l-2 shift valvebetween a [-2 shift valve element 310 and a shift control valve element312. This pressure moves the l-2 shift valve element 310 to thedownshifted position to exhaust chamber 1 12 of the intermediate brake108 as will be further explained below. The pressure in chamber 308 alsomoves the l-2 shift control valve element 312 to the upshifted positionwhich sends apply oil to the low and reverse chamber 84. Once the manuallow control valve element 290 is in the downshifted position, the spring292 plus low apply oil acting on the valve element will maintain thevalve element in this position. Thus with the transmission in manuallow, the transmission cannot upshift regardless of vehicle or enginespeed once low gear has been engaged.

The l-2 shift valve 306 controls the supply of drive line oil to theservomotor for the intermediate brake to cause the transmission to shiftbetween low and second. This valve is controlled by governor pressureacting on shift valve element 310 andmodulator shift valve pressure andspring force acting on shift control valve element 312. The spring forceon this latter valve element is provided by a spring 318 located in apressure chamber 320 which engages the shift control valve element anddetermines the minimum shift speeds.

The hydraulic pressures which control the forces on this valve aremodulator shift valve pressure fed to port 319 and to pressure chamber320 by modulator shift valve line 258 and detent-2 pressure fed into theshift valve through spaced ports 322 and 324. The end area of the righthand spool or land controls the part throttle upshift schedule; thesecond or next spool has an area that controls the wide open throttle2-l downshift point. The area of the third land 0 controls the wideopenthrottle l-2 upshift. The shift control valve element 312 also supplieshydraulic pressure to the chamber 84 of the low and reverse brake 78through port 326 and the line 85 leading to the chamber 84 when thetransmission is conditioned for manual, low or reverse. This shiftcontrol valve has reverse port 328 connected to reverse line 87 leadinginto chamber 86 of low and reverse brake 78 and leading into chambers 98and 99 of reverse clutch 102. When shift control valve 312 is upshifted,U-shaped passage 330 connects detent-2 port and detent-2 line 246 tochamber 320 to pressurize chamber 320 to provide for wide-open throttle2-1 downshifts in response to movement of the detent valve element 228to the D position.

The shift valve element 310 has two lands a and 11; land a is acted onby governor pressure fed to an end pressure chamber 337 through line200. The differential area between the two spools gives the valvehysteresis which is an additional force to the right supplied bypressure from drive line 184 when the valve moves to the upshiftedposition. Thus, this shift valve is controlled by the force of governorpressure plus drive pressure acting on the hysteresis area lands a and bwhen valve element 310 is in the upshifted position. When the shiftvalve is in the downshifted position, the l-2 clutch line 114 connectedto port 338 in the l-2 shift valve is exhausted by an exhaust port 340having a flow control restriction. As the shift valve moves to theupshifted position, drive pressure through drive line port 344 isconnected to the l-2 clutch line 114 and is fed by this line directly tothe apply chamber 345 of a servo 346 which operates brake band 103. Theservo has a release chamber 348 connected to a servo control line 352.This control line can be connected to the RND pressure by a 2-3 shiftvalve 354 when downshifted so that the servo cannot apply brake band103. The l-2 clutch pressure supplied through shift valve element 310 toclutch line 114 is transmitted through a 1-2 upshift restriction 356 andthe shift check valve 358 to a l-2 accumulator 360 and to intermediateclutch apply chamber 112. The accumulator 360, l-2 orifice 356 and applychamber 112 are combined to give a smooth shift transition from first tosecond. A 2-1 shift check valve 364 and restriction 366 cooperates withthe l-2 shift check valve 358, restriction 356 and the exhaust port 340of the l-2 shift valve to provide control of 2-1 downshifts.

The 2-3 shift valve 354 controls shifts between second and third. Thisvalve has a control valve element 370 and a shift valve element 372. Thecontrol valve element transmits the force exerted by a spring 374disposed in a spring pocket provided by pressure chamber 376 to theshift valve element 372. Modulator shift valve pressure supplied throughline 258 is fed to port 378 controlled by the end land a of the controlvalve element 370. In the downshifted position, this valve elementpermits modulator shift valve pressure to be fed to the chamber 376 forpart throttle upshifting. The force exerted by modulator shift valvepressure on the shift control valve element 370 is relayed to shiftvalve element 372.

The 3-2 part throttle line 262 is connected to an inlet port 380 betweenthe first and second lands a and b of valve element 370 having an areadifferential so that 3-2 part throttle pressure urges the shift controlvalve to the downshift position. Detent-2 pressure from the detent valvethrough line 246 is fed to a port 382 between the second and third landsb and c to act on the area differential of these lands to urge thecontrol valve element 370 and the shift valve element 372 to adownshifted position. U-shaped passage 384 connecting port 386 withchamber 376 transmits detent-2 pressure from line 246 into chamber 376when the shift control valve is upshifted. The right side area of theland controls the part throttle 2-3 upshift schedule up to the 3-2position of the detent valve. After the 3-2 position of the detentvalve, the part throttle upshift schedule becomes controlled by the areaof land b. The difference in area between mentioned lands a and bcontrols the 3-2 part throttle downshifts. The area of land 0 controlsthe through D detent upshifts and downshifts.

The shift valve element 372 has governor pressure from line 200 fed intoan end chamber 388 that urges shift valve element 372 to an upshiftposition. There is a spring 390 disposed in a central chamber 394 actingon an end of the shift valve element 372 opposing the force of governorpressure. The sum of springs 390 and 374 determines the minimum shiftspeeds.

intermediate pressure from the manual valve 178 supplied to intermediateline 186 is ported to chamber 394 to move the shift valve to thedownshifted position whenever intermediate line 186 is pressurized.

When the shift valve element 372 is downshifted, a RND- port 392connected to the RND-line 192 is connectedto a servo port 395 connectedto servocontrol line 352 to pressurize the control chamber 348 of theservo 346.

Converter charge pressure from the pressure regulator valve is fed byline 118 into a port 396 of the 23 shift valve. This port is connectedto a 2-3 accumulator port 398 for a 2-3 accumulator line 400 when the2-3 shift valve is downshifted. In this valve position a third signalport 402 connected to third range signal line 404 is exhausted throughexhaust 401. When the 2-3 shift valve element 372 moves to the upshiftedposition, the servo port 395 is connected to a forward clutch port 470connected to forward clutch line 46 which is pressurized with drive oilfrom the 3-4 shift valve 216 provided the 3-4 shift valve is in thedownshifted position. Under these conditions the servo can not effectthe engagement of brake band 103. The 2-3 accumulator port 398 isexhausted and the third signal port 402 which was exhausted becomespressurized with drive oil. This drive oil also acts on a differentialarea of the shift valve giving the shift valve hysteresis control.Pressurizing the third signal port 402 and exhausting the 2-3accumulator ports 398 activates a 2-3 accumulator control valve 406resulting in a 2-3 shift.

The 2-3 accumulator control valve 406 is provided to control the frontclutch 55 so that it engages properly during a 2-3 shift. This clutch isapplied when chamber 59 is exhausted and converter pressure acting onplate 54 moves it forwardly to effect the engagement of clutch 55.

The 2-3 accumulator control valve includes a regulator valve 408 whichis urged in one direction by a spring 410 disposed in a pocket formed bypressure chamber 412 located at one end of the valve. Converter feedpressure from line 118 is ported into this chamber. This pressure isalso fed into chamber 413 through port 409 that is controlled by thefirst land of regulator valve 408. A suitable passage through this landconnects chamber 413 with a control chamber 415. Converter clutch port416 is connected to converter clutch line 61. This line has a branchline 418, having restriction 420 and check valve 422, leading into the2-3 accumulator line 400. This latter line is connected to the 23accumulator valve by port 426.

To provide an upshift force on the regulator valve 408 the 2-3accumulator has a boost valve 428 which is disposed in a support locatedwithin the valve body. The boost valve is seated on the end of coilspring 430 which extends from a pocket formed in an accumulator piston432 movably mounted in the valve body. The accumulator piston is urgedtoward the boost valve or the upshift position by a spring 434. Driveline pressure from line 184 is fed into the chamber 436 to provide adownshift bias on the accumulator piston.

The accumulator piston is so designed that when it is to the full leftposition, it fully compresses the spring 430 and forces the boost valveand regulator valve to the full left position. When drive line pressurehas forced the accumulator piston to the right which is the downshiftposition, the spring 434 will be fully compressed. The 2-3 accumulatorline 400, port 426 and converter clutch branch line 418 are pressurizedwith converter charge pressure fed to the 2-3 shift valve through line118. The 2-3 accumulator line and the converter branch line 418 are alsoconnected through the 3-2 shift check valve 422. The converter clutchcircuit 61 is therefore pressurized with converter pressure releasingthe converter clutch. When a 2-3 shift is signaled by the 2-3 shiftvalve 354, the 2-3 accumulator line 400 is exhausted through exhaust 401in the 2-3 shift valve; the 3-2 shift check valve 422 seals allowing the2-3 accumulator valve to regulate converter pressure.

The 2-3 accumulator valve has a pressure chamber 438 connected by athird signal port to the third signal line 404 through check valve 442and restriction 446. When chamber 438 is fed with third signal pressureequalizing pressure forces on the accumulator piston 432, the spring 434pushes the accumulator piston to the left-hand position. The springs 434and 430 must be selected so that the accumulator piston, acting throughthe boost valve can push the regulator valve 408 to the far left-handposition so that the 2-3 accumulator port 426 is open to exhaust theconverter clutch circuit 61 completely so that the converter clutch fullcapacity can ultimately be attained. FIG. 3 illustrates the clutch applysequence as controlled by the 2-3 accumulator valve.

This graph shows the clutch 55 disengaged by converter pressure P untilthe 2-3 shift valve signals an upshift and clutch engagement at point 1.The third signal line 404 is pressurized with drive line oil and thechamber 438 fills with oil flowing through flow control construction446; the chamber expands while the converter feed restrictor valve 162opens the supply of oil to the converter through converter feed line 118as the restrictor valve element 460 is moved to the left against spring462. At point 2 where clutch engagement has been made, the accumulatorpiston has moved the regulator valve to a far left position to fullyopen the converter clutch line 61 to exhaust through line 400 providingfor the full torque transmitting capacity of clutch 55. Thus it can beseen that the accumulator system controls the clutch apply in terms ofdrive pressure which is sensitive to engine torque and vehicle speed aswell as being sensitive to the two calibration springs 430 and 434. Thissystem is not sensitive to converter pressure which is not easy tocontrol in a transmission. in this control system the clutch is fullyreleased prior to point 1 and engaged with full capacity after point 2.The engagement time is established by the restriction 446 in the thirdsignal line 404, the accumulator valve oil volume, and springs 430 and434. This slope of the converter clutch pressure is controlled by therate of spring 430. During downshifts, the accumulator valve system isbypassed by the shift check valve 422 and restriction 420.

The 3-4 shift or forward clutch control valve 216 consists of threevalves formed by control valve elements 470, 472 and a shift valveelement 474. The control valve 472 has end chamber 475 connected toconverter feed line 118 so that converter feed pressure operates on thelarge area of the land of control valve element 472. This pressure isconnected to a chamber 478 on the left side of this spool by a flowcontrol passage in the land. Chamber 478 is connected to an exhaust 480through a line controlled by a solenoid operated valve 484. The solenoidof this valve is controlled by electric switch 485. When the switch isopen the solenoid is deenergized and the exhaust 480 is sealed so thatthe transmission can shift into fourth range if modulator pressure isless than a set minimum. When the switch 485 is closed the solenoid isenergized and the chamber 478 is exhausted through the open exhaust 480.A spring in chamber 478 urges the valves toward the right. When thesolenoid is energized, exhaust 480 is opened and chamber 478 isevacuated, the valve element 472 will be moved to the left by pressurein chamber 475 pushing 3-4 shift control valve 470 to its full leftposition compressing coil spring 481. Thus the solenoid, when energized,deactivates the 3-4 valve system so that shifts to fourth cannot be madeand when deenergized makes the selection of the fourth operating gearpossible.

The second control valve 470 is a simple two position valve; however, itcan only function when the first control valve element 472 is in theright-hand position with chamber 478 pressurized. Valve 470 is urged tothe left by a control pressure fed through a control line 482 to achamber 483 at one end of valve 470. This control pressure holds thecontrol valve element 470 in its full left position when it is above apredetermined pressure level and allows it to return to the full rightposition when it is below this selected pressure level. When valve 470is in its left position, drive line pressure from line 184 is connectedto an intermediate port 486 which is connected to a branch line 488leading through a check valve 490 to a pressure chamber 492 at the endof the 3-4 shift valve element 474 so that this valve cannot upshiftwhen this chamber is pressurized. The check valve also connects thebranch line 488 to the intermediate line 186. If the shift control valve470 were in its right-hand position, chamber 492 of the shift valveelement 414 is connected to the converter clutch line 61 through branchline 488 and check valve 490. A 3-4 shift could now occur providing asufficient governor pressure supplied through line 200 to a pressurechamber 494 which is available to counteract the force of the springdisposed in chamber 492 urging the 3-4 shift valve element 474 to theleft. For a 3-4 shift, it is necessary that the converter clutch line 61be exhausted signaling that the transmission is completely shifted intothird gear. It can, therefore, be seen that three requirements must bemet before the 3-4 shift valve can signal a 3-4 shift when sufficientgovernor pressure is available. They are (l) the solenoid operated valve484 must be deenergized, (2) control pressure must be below apredetermined pressure, (3) converter clutch system must be exhausted.The intermediate check 490 situated between the control valve element470 and the shift valve element 474 will downshift the transmission outof fourth gear if manual intermediate or manual low range is selected.

The shift control valve element 474 has three main functions. In thedownshift position, as shown, modulator pressure from line 210 which isa function of engine torque only, is connected to the control line 482.This allows 3-4 shifts to only take place at very low engine torques. Inthis position of valve element 474 drive line 184 is connected to theforward clutch line 46 and this pressure holds the forward clutchengaged and keeps the servo 346 released since the 2-3 shift valveelement 372 is in the upshifted position. The main pressure boost line172 is connected to port 500 of the 3-4 shift valve. In the downshiftedposition the boost line 172 is exhausted through an exhaust 502. Whenconditions are such that an upshift occurs, the control line 482 isconnected to the detent port 504 of detent-l line 250. This keeps thecontrol line 482 exhausted unless the detent-I port at the detent valve226 becomes pressurized which would move 3-4 control valve 470 over tothe left and signal a 4-3 downshift. In the upshifted position of theshift valve element 474, the forward clutch line 46 is connected intoexhaust 502 which will exhaust the chambers 41 and 42 to release theforward clutch. The servo control line 352 is exhausted since the 2-3shift valve is in the upshifted position and the servo port 395 isconnected to forward clutch port 407. Exhaust 502 is above the oil levelsince the forward clutch 32 is released and rotating in fourth gear.

In the upshifted position of the 3-4 valve element 474, the boost port500 and boost line 176 become pressurized with oil from drive line 184.The first land of the shift valve element 474 has a larger diameter thanthe other lands to give it the required amount of shift hysteresis forsubsequent downshifts. The boost line 172 connects to a boost checkvalve 508 where it is blocked from entry into the intermediate line 186and is properly routed to the boost plug chamber 170 in the mainpressure regulator valve system, therefore, boosting line pressure infourth. The boost check valve 508 controls the boost plug 150 of themain pressure regulator valve system so as to boost line pressure inmanual intermediate and low gear ranges and also in fourth gear.

There is a converter out restrictor valve 510 in addition to theconverter feed restrictor valve 162. Both of these valves are twoposition systems. Third signal pressure from line 404 is fed to an endchamber 512 to force the valve element 514 to the left against spring516 to block the flow of converter discharge fluid through valve 510forcing the flow through flow control restriction 518 to a cooler 520and a lubricant passage 522. When oil flow through the converter iscontrolled by the restriction 518 bypassing valve 510, the converterfeed restrictor valve 162 opens the converter feed line 118 since thirdsignal pressure pushes restrictor valve element to the illustratedposition.

For automatic drive, the vehicle operator by actuating the manualcontrol, places the manual valve element 180 in the automatic driveposition D. In this position regulated main line pressure is fed throughthe manual valve to the drive line 184. Since governor pressure is lowand torque demand is high, all of the shift valve elements will be intheir downshifted position. Underthese conditions the forward clutchline 46 and forward clutch chambers 41 and 42 are fed with drive lineoil through the 3-4 shift valve to effect engagement of the forwardclutch 32. With forward clutch 32 engaged, the sun gear 48 will bedriven forwardly. The one-way brake automatically engages to hold thering gear for reaction to condition the transmission for forward lowspeed operation.

The converter clutch 55 is released in low range since the regulatorvalve element 408 of the 2-3 accumulator control valve supplies theconverter clutch port 416 and line 61 with regulated converter feedpressure. With regulated pressure fed by line 61 into the converter byway of clutch release chamber 59 clutch 55 is disengaged.

There is no feed of oil to the converter through line 118 and passage120 at this time since the converter feed restrictor valve element 460is blocking feed line 118 in the absence of third signal pressure inline 404. Fluid exiting from the converter goes through passage 124, theconverter out valve 510 and through the cooler to lubrication passage522.

As vehicle speed increases and torque demand decreases the 1-2 shiftvalve is forced by increasing governor pressure to the upshiftedposition. In this position of the l-2 valve element, drive line oilthrough port 344 is connected to the I-2 clutch line 114. This oil isrouted to the 1-2 accumulator 360 whose piston moves to the left toincrease its volume to calibrate the shift as oil fills intermediatechamber 112 so that piston effects the engagement of intermediate brake108. The forward clutch 32 is still engaged since the 3-4 shift valve isin the downshift position. With clutch 32 and brake 108 engaged thegearset will be conditioned for second speed drive. One-way clutch 106is locked and one-way brake 90 is overrunning as described.

in second range automatic drive 1-2 clutch oil is fed from the upshiftedl-2 shift valve via line 114 into the apply chamber 345 of the servo ofbrake band 103, however. this does not effect brake band apply since therelease chamber' 348 is fed with oil from line 352 connected to the RNDline 192 when the 2-3 shift valve is in the downshifted position. As.

in low range the converter is fed through the converter clutch line 61.

As torque demand further decreases and vehicle speed further increases.the '2-3 shift valve 372 upshifts. 1n the upshifted position of thevalve element 372, pressure fromdrive line 184 is connected to the thirdsignal port 402 and third signal line 404. The 2-3 accumulator line 400becomes open to the exhaust 401. When the third signal line ispressurized, the 2-3 accumulator valve shifts in response to thirdsignal pressure in chamber 438 so that converter clutch line 61 isconnected to 2-3 accumulator line 400 and is exhausted through exhaust401 in the 2-3 valve. The third signal pressure acts on the end land ofthe converter feed restric'tor valve element 460 to shift that valve sothat a converter feed is establishe in line 118. This pressure istransmitted bypassage 120 into the converter inlet. The converter outrestrictor valve element 514 is shifted so that the converter dischargeinto passage 124 is fed through the restriction 518 into the cooler 520and then into the lubrication passage 522. With the cont sure thechambers 41 and 42 and maintain the engagement of the forward clutch 32.With forward clutch 32 applied in addition to the front clutch 55 thegearset 38 is driven hydraulically and mechanically to provide a 1:1split torque ratio.

Under conditions such as open highway cruising the 3-4' shift may bedesired for high economy operation. This selecpressure is effective inchamber 492 of the 3-4 shift valve, to urge the 3-4 shift vaive eiement474 to the downshifted position so that pressure from drive line 184 isconnected to the forward clutch line 46 to effect engagement of forwardclutch 32. Drive line oil is connected to the 1-2 clutch line 114 sincethe l-2 shift valve is in the upshifted position. This effects theengagement-of the intermediate brake 108.

For manual low range. the manual valve is set in the L, position so thatregulated pressure is supplied to drive line 184. inte'rmediate driveline 186 and low range line 182. At vehicle speed below a predeterminedspeed the low control valve element 290 is shifted by the coil spring toopen the low range port 298 to port 300 of manual low line 302. This oilis fed into the chamber 308 of the 1-2 shift valve. The force exerted bythe pressure 011 in this chamber moves the shift valve element 310 tothe downshifted position and the shift control valve element 312 to theupshifted position. Under these conditions manual low pressure is fedinto port 326 of the low and reverse line 87 to effect the engagement ofbrake 78.

The forward clutch 32 is applied since the intermediate line i 186 ispressurized in this manual valve position to downshift the 3-4 shiftvalve element 474 by pressurizing chamber 492.

' In this position the 3-4 shift valve connects the drive line to tiveshift is madepossible by opening switch 485 so that the solenoid isdeenergized to allow the 3-4 shift valve to upshift. The forward clutchapply chambers 41 and 42 and line 46 are exhausted through exhaust 502;the fonvard clutch 32 disengages. At this time brake band 103 engagesdrum 94 to hold sun gear 70 for reaction since the servo release chamber348is I exhausted. This occurs because the 2-3 shift valveis upshiftedand the'servo line 352 is connected by the 2-3 shift valve element withthe forward clutch line46. The upshifted 3-4 shift valve element 474exhausts the servo release oil through the connection of forward clutchline 46 with exhaust 502.

Since the shiftvalve element 310 of the 1-2 shift valve is in theupshifted position as in second and third. drive line oil is connectedto intermediate clutch port 338-and line 114. With forward clutch line46.

For reverse. the manual valve is moved to the position R toconnectreverse line 87 and the RND-line 192 to regulated main line pressure.Reverse oil from line87 is fed into reverse chamber 86-to effect theengagement of low and reverse brake 78. The 1-2 shift valve elements 310and 312 being downshifted will feed reverse line oil from line v87' intoport] v 326 so that low and reverse chamber 84 will be pressurized toincrease the torque capacity of brake 78. Since reverse clutch line 87is connected with reverse chambers 98 and 99. the reverse clutch 102 isapplied.

Line pressure is boosted to increase the capacity of the engagedfriction devices in reverse. This pressure boost occurs because reverseline pressure is fed into chamber 149 and the modulator trim and reverseboost valve element 148 is forced by reverse pressure into biasingengagement against the main regulator valve element so that it regulatesa higher main line pressureline 142. x

The detent valve element 228 is mechanically connected to the throttlelinkage and is appropriately moved in direct response to throttle pedalmovement to provide for 3-2 and 4-3 part throttle downshifts and wideopen throttle 3-2 and 2-1downshifts.

A 3-2 part throttle downshift can be made'belo'w a predetermined vehiclespeed, mph. for example. At light throttle the detent valve-is releasedand the 3-2 part throttle line 262 is exhausted through exhaust port261. When an'increased torquedemand is'made. thedeten't valve element228 can bemoved tothe 3-2 position so that the 3-2 part throttle servocontrol chamber 348 exhausted, pressure fed by line 114 to servo chamber345 effects the engagement of band 103 as well as the intermediate brake108.

As will be appreciated, this control will provide for automaticdownshifting in response to increasing torque demand and decreasingsignals by the movement of the respective shift valves to theirdownshift positions.

For manual intermediate drive; the manual valve is moved to the L,position. in this position the manual valve connects pressure from mainline 14210 drive line 184 and intermediate line 186. The lowrange-driveiine is exhausted through passage 187 and exhausts 188.-Also; the RND-line 192 and reverse line 87 are connected to exhausts188. Under these conditions. pressure from intermediate line' 186 actson the and land of 2-3 shift valve element 372 to urge it to the line262 isconnected to modulator trim pressure line 218. Pressure fluid isfed through the 3-2 part throttle line 262 to port 380 in the 2-3 shifivalve. The pressure buildup in the associated pressure chamber forcesthe 3-2 control valveelement 370 and the 2-3 shift valve element 372' tothe downshifted position. in this position the third signal line isexhausted so that the converter feed restrictor valve blocks the supplyof fluid to the converter through converter feed line 118. However, theconverter is supplied with oil through feed line 61 since line 118 isconnected bythe 2-3 shift to the accumulator line 400. The 2-3accumulator control valve element shifts so that converter clutch feedline 61 and feed passage 60 is-connected to converter feed line 118. Thesupply of pres-- sure fluid into clutch chamber 59 effects disengagementof clutch 55. The intermediate brake 108 is applied since the l-2 shiftvalve element is in the upshift position and drive line downshiftedposition and also on boost plug 150 raising f minimum line pressure. Theservo control chamber 348 is'exhausted since servo control line 352' isconnected .by the downshifted 2-3 shift valve element to the RND-line192 which is opened at the manual valve to exhaust. intermediate.pressure is connected to the I-2 clutch line 184. The forward clutch isapplied since the 3-4 shift valve is in downshifted position and driveline oil is fed intoforward clutch line through line 46. Modulator shiftvalve oil fed from the detent valve through line 258 to the 2-3 shiftvalve opposes governor pressure so that the shift schedule is changed.

The 4-3 part throttle downshift can be obtained by moving h i the detentvalve to the 4-3 of D-l position. in this valve element position, the3-2 part throttle line 262 is connected to port 225 and is fed withmodulator trim pressure. Also, the modulator shift valve line 258 is fedwith modulator trim pressure. Thedetent-i line is fed a regulatedpressure from the detent regulator valve 254.

The 3-4 shift valve element is in upshifted position and detentregulator oil is fed by the detent-i line to the chamber 217. This oilis then fed into the control line 482 which leads to control chamber 483between the control valve elements 470 and 472. The control valveelement 470 is downshifted to connect drive line pressure to theintermediate branch line 488; Drive pressure in chamber 492 of the 3-4shift valve causes this valve to downshift. The intermediate check ballseats to prevent any other flow in this line.

With the 3-4 shift valve downshifted, drive line oil is again fed to theforward clutch line 46 to apply forward clutch 32. The servo 346 for thebrake band [03 is released by the supply of forward drive oil being fedinto servocontrol line 352 in the 2-3 shift valve. The 2-3 accumulatorstays upshifted so that convertcrclutch line 61 is connected to the 2-3accumulator line 400 which is open to exhaust 401 at the 2-3 shiftvalve. This'exhaust of the converter clutch control chamber 59 allowsconverter pressure to effect engagement of the front clutch 55. Theclutch 55 is engaged in both direct and overdrive. The intermediateclutch is also engaged through the upshifted 1-2 shift valve.

Wide open throttle 4-2, 3-2 and 2-1 downshifts are obtained by placingthe detent valve in the D-2 position. The 3-2 part throttle line 262remains connected to the modulator trim line 218 so that the 2-3 shiftvalve element is urged by the shift control valve 370 to the downshiftedposition. The modulator shift valve line 258 is connected to themodulator trim line 218. The detent-2 line 246 is connected to thedetent regulator pressure fed through line 276; detent regulatedpressure is fed by the detent-2 line to the 1-2 and 2-3 shift valves. inthe upshifted position this pressure is fed to the shifi control valveelements 312 and 370 to urge them toward the downshifted position. ifthe vehicle is cruising in direct drive, a wide open throttle causes a3-2 downshift above a premetermined speed and a 3-1 downshift below thatspeed. If the vehicle were operating in fourth gear, a 4-2 downshiftwould be accomplished.

This invention is not limited to the details of the construction shownand described for purposes of illustrating the invention for othermodifications will occur to those skilled in the art.

What is claimed is:

l. in a transmission having an input and an output, a hydrodynamictorque transmitting unit having an input rotor operatively connected tosaid input and having an output rotor, a change speed-gearing unitdrivingly connecting said output rotor and said transmission output,torque-transmitting means drivingly connected to said changespeed-gearing unit, selectively engageable clutch means disposed withinsaid hydrodynamic unit for drivingly connecting and for disconnectingsaid torque-transmitting means and said input, hydraulically operatedmotor means within said hydrodynamic unit for effecting the engagementand disengagement ofsaid clutch means, a plurality of friction driveestablishing devices including a forward drive clutch and a brakeoperatively connected to said gearing unit and selectively engageabie toproduce a plurality ofdifferent input/output speed ratios; control meansfor said friction drive establishing devices and said motor means ofsaid clutch means comprising shift valve means responding to signalsproportional to the rotational speed of said output and opposingdecreasing signals represe nt tative of torque demand from saidtransmission by shifting to exhaust said forward drive clutch and applysaid brake to condition said transmission for its smallest input/outputspeed ratio and further to produce a control signal to effect exhaust ofsaid motor means so that fluid in said hydrodynamic unit effectsengagement of said clutch means for an all mechanical drive.

connected to said controls for controlling the engagement anddisengagement of said clutch means.

3. The transmission defined in claim 2 and further including springmeans disposed within said converter and contacting said motor means forurging said motor means in a direction for engagement of said clutchmeans.

4. in .a transmission having an input and an output, a hydrodynamictorque converter having a housing with pump means operatively connectedto said input and having turbine' means, a change speed gearing unitdrivingly connected to said output, first torque transmitting meansdrivingly connecting said turbine to said gearing unit, second torquetransmitting means drivingly connected to said gearing unit,hydraulically operated forward drive clutch means operatively disposedin said first torque-transmitting means and selectively engageable topermit said turbine means to drive said gear.- ing unit, brake meansoperatively connected to said gearing unit selectively engageabie toproduce the smallest torque ratio when said second torque-transmittingmeans is driven, hydraulically operated clutch disposed within saidhousing'of said converter engageabie by fluid within said converter toprovide for the mechanical drive of said gearing unit by saidtransmission input and disengageable to provide for the all hydraulicdrive of said gearing unit by said torque converter when said forwarddrive clutch means is engaged, as source of v regulated fluid pressure,a plurality of shift valve means operatively connected to said sourceand to said clutch means for upshifting and downshifting said gearingunit, one of said shift valve means responding to an increase in speedof said transmission output and a decrease in torque demand by upshifting to effect engagement of said clutch within said converter, andanother shift valve meanspositionabie to supply a pressure fluid to saidforward drive clutch means to effect the engagement thereof and tosupply a pressure fluid to said first mentioned valve for subsequentsupply to said brake means to prevent the engagement thereof, saidsecond shift valve means having exhaust means for exhausting saidforward drive clutch means and said brake means in the upshift positionof said second shift valve means to effect disengagement of said clutchand engagement of said brake to provide for the smallest torque ratiodrive.

5. The transmission defined in claim 4', a hydraulically operatedservomotor for said brake means. fluid passage means operativelyconnecting said servomotor to said first mentioned valve means, and anadditional shift valve means operatively connected to said source and tosaid brake means to supply pressure fluid to said brake means to effectrelease of said brake means in response to the upshift upshifling ofsaid last and second-mentioned shift valves.

6. in a transmission having an input and an output, a hydrodynamictorque-transmitting unit having an input rotor operatively connected tosaid inputand having an output rotor, a change speed gear unit drivinglyconnecting said output rotor and said transmission output,torque-transmitting means drivingly connected to said gear unit,selectively engageable clutch means for drivingly connecting and fordisconnecting said torque-transmitting means and said transmissioninput, hydraulically actuated motor means for operating said clutchmeans, a source of fluid pressure, first feed means operativelyconnected to saidsource for feeding said hydrodynamic unit, shift valvemeans operatively connected to said source and positionable in a firstposition in response to predetermined torque to route converter feed oilto said motor means to effect disengagement of said clutch and controlvalve means responding to a signal pressure from said shift valve meansby routing fluid from said clutch to exhaust at said shift valve meansto permit hydrodynamic unit pressure to effect engagement of saidclutch.

7. In a transmission having an input and an output, a hydrodynamictorque converter having a housing with pump means operatively connectedto said input and having turbine means, a change speed planetary gearunit having first and second inputs and having an output drivinglyconnected to said transmission output, a plurality of friction driveestablishing devices operatively connected to said gear unit which areselectively engageable to produce first, second and third input/outputspeed ratios, a fluid-operated clutch disposed in said converter andengaged by fluid within said converter for drivingly connecting saidtransmission input with said second input of said gearset, means forsupplying fluid to said converter for releasing said clutch, a source offluid pressure, a plurality of shift valves operatively connected tosaid source and to said friction drive establishing devices for shiftingsaid transmission between predetermined input/output speed ratios, anaccumulator valve means operatively connected to said clutch to controlthe engagement thereof, said accumulator valve having an accumulatorchamber for collecting a signal pressure from said shift valve means andsubsequently shifting to route oil from said converter clutch to saidshift valve means and to an exhaust whereby said converter clutch isengaged by working fluid within said converter.

8. In a transmission having an input and an output, a hydrodynamictorque converter having a housing with pump means operatively connectedto said input and having turbine means, a change speed planetary gearunit having first and second inputs and having an output drivinglyconnected to said transmission output, a plurality of hydraulicallyactuated friction drive establishing devices operatively connected tosaid gear unit which are selectively engageable to produce a pluralityof different input/output speed ratios, a fluidoperated clutch disposedwithin said converter and engageable by fluid therein for drivinglyconnecting said transmission input with said second input of saidgearset, a source of fluid pressure, shift valve means responding topredetermined operating signals of said transmission for routingoperating oil to said clutch within said converter to effect thedisengagement thereof to provide for all hydraulic drive of said gearunit by said converter, control valve means operatively connected tosaid shift valve means and movable in response to a signal pressure fromsaid shift valve means to connect said clutch means with an exhaust insaid shift valve means to effect the rapid exhaust of said clutch andthe engagement of said clutch by working fluid within said converter.

9. In a transmission having an input and an output, a hydrodynamictorque converter having pump means driven by said input and havingturbine means, a planetary gear unit operatively connected to saidoutput, torque transmitting means drivingly connecting said turbinemeans to said planetary gear unit, a plurality of friction driveestablishing devices operatively connected to said gear unit andengageable to condition said transmission for a plurality of forwarddrive input/output gear ratios, said torque converter having a housingconnected to said pump means and driven by said input, clutch meansoperatively disposed in said housing, a torquetransmitting shaftdrivingly connecting said clutch means and said planetary gear unit, aclutch support hub secured to said torque-transmitting shaft, a pressureplate having a friction surface engageable with said housing forming aportion of said clutch means mounted for longitudinal sliding movementon said support, said plate and said housing forming a chamber therein,control means for said transmission including first means for feedingconverter charge fluid to said chamber to effect movement of said platefrom engagement with said housing to effect disengagement of said clutchmeans and the exhaust fluid from said chamber, and including secondmeans for feeding fluid into said converter when said first means isexhausting fluid from said converter so that converter pressure effectsengagement of said clutch means. I

10. The transmission defined in claim 9 wherein said controls include aplurality of shifter valves operatively connected to said friction driveestablishing device and an accumulator valve for controlling theengagement of said clutch, said valve having an accumulator piston whichforms a pressure chamber connected with said shift valve, said chamberbecoming charged with pressure fluid from said valve when said shiftvalve upshifts said accumulator piston operating on a boost valve tomove the regulator valve to a position whereby the converter clutch lineis opened to the two-three accumulator line and is exhausted at shiftvalve to calibrate the engagement of said clutch. I

11. In an automatic transmission having an input and an output, ahydrodynamic unit having an input rotor and having an output rotor, ahousing for said unit driven by said input and drivingly connected tosaid input rotor, change speed gear means drivingly connecting saidoutput rotor to said transmission output, a plurality of friction driveestablishing devices operatively connected to said gear means andselectively engageable for changing the input/output speed ratio of saidtransmission, a clutch in said housing of said hydrodynamic unit, saidclutch having clutch drive means driven by said input, and clutch-drivenmeans drivingly connected to said gear means, a supporting plate formingpart of said driven means and cooperating with said housing to form apressure chamber, control means for said friction drive establishingdevices and said clutch means comprising a source of fluid pressure, aplurality of shift control valve means operatively connected to saidsource and said friction drive establishing devices, torque demand andoutput speed signal means operatively connected to said shifter valvemeans for upshifting and downshifting said valve means, an accumulatorvalve means operatively connected to said source and at least one ofsaid shift valve means, said accumulator valve having regulator meansfor supplying regulated pressure to said chamber to effect disengagementof said clutch means and to feed said hydrodynamic unit, saidaccumulator valve having an accumulator valve element movable to apredetermined position to effect-the exhaust of said chamber so thatpressure within said unit will effect the engagement of said clutch.

12. The automatic transmission defined in claim 11, said clutch-drivenmeans comprising a supporting hub having an annular shoulder, saidsupporting plate having a sleeve portion for mounting said plate on saidsupporting means, drive means for drivingly connecting said plate andsaid supporting means while permitting axial movement of said plate, andspring means disposed for urging said clutch drive and driven means intodrive engagement with each other.

1. In a transmission having an input and an output, a hydrodynamictorque transmitting unit having an input rotor operatively connected tosaid input and having an output rotor, a change speed-gearing unitdrivingly connecting said output rotor and said transmission output,torque-transmitting means drivingly connected to said changespeed-gearing unit, selectively engageable clutch means disposed withinsaid hydrodynamic unit for drivingly connecting and for disconnectingsaid torquetransmitting means and said input, hydraulically operatedmotor means within said hydrodynamic unit for effecting the engagementand disengagement of said clutch means, a plurality of friction driveestablishing devices including a forward drive clutch and a brakeoperatively connected to said gearing unit and selectively engageable toproduce a plurality of different input/output speed ratios; controlmeans for said friction drive establishing devices and said motor meansof said clutch means comprising shift valve means responding to signalsproportional to the rotational speed of said output and opposingdecreasing signals representative of torque demand from saidtransmission by shifting to exhaust said forward drive clutch and applysaid brake to condition said transmission for its smallest input/outputspeed ratio and further to produce a control signal to effect exhaust ofsaid motor means so that fluid in said hydrodynamic unit effectsengagement of said clutch means for an all mechanical drive.
 2. Thetransmission defined in claim 1 wherein said hydrodynamic unit comprisesa torque converter having a housing operatively connected to said inputand to said input rotor, said clutch means comprising a friction surfaceon the inside of said housing and a cooperating friction surface on saidmotor means, support means mounting said motor means for sliding axialmovement to effect engagement and disengagement of said clutch means,said motor means and said housing cooperating to form a pressure chamberoperatively connected to said controls for controlling the engagementand disengagement of said clutch means.
 3. The transmission defined inclaim 2 and further including spring means disposed within saidconverter and contacting said motor means for urging said motor means ina direction for engagement of said clutch means.
 4. In a transmissionhaving an input and an output, a hydrodynamic torque converter Having ahousing with pump means operatively connected to said input and havingturbine means, a change speed gearing unit drivingly connected to saidoutput, first torque transmitting means drivingly connecting saidturbine to said gearing unit, second torque transmitting means drivinglyconnected to said gearing unit, hydraulically operated forward driveclutch means operatively disposed in said first torque-transmittingmeans and selectively engageable to permit said turbine means to drivesaid gearing unit, brake means operatively connected to said gearingunit selectively engageable to produce the smallest torque ratio whensaid second torque-transmitting means is driven, hydraulically operatedclutch disposed within said housing of said converter engageable byfluid within said converter to provide for the mechanical drive of saidgearing unit by said transmission input and disengageable to provide forthe all hydraulic drive of said gearing unit by said torque converterwhen said forward drive clutch means is engaged, a source of regulatedfluid pressure, a plurality of shift valve means operatively connectedto said source and to said clutch means for upshifting and downshiftingsaid gearing unit, one of said shift valve means responding to anincrease in speed of said transmission output and a decrease in torquedemand by upshifting to effect engagement of said clutch within saidconverter, and another shift valve means positionable to supply apressure fluid to said forward drive clutch means to effect theengagement thereof and to supply a pressure fluid to said firstmentioned valve for subsequent supply to said brake means to prevent theengagement thereof, said second shift valve means having exhaust meansfor exhausting said forward drive clutch means and said brake means inthe upshift position of said second shift valve means to effectdisengagement of said clutch and engagement of said brake to provide forthe smallest torque ratio drive.
 5. The transmission defined in claim 4,a hydraulically operated servomotor for said brake means, fluid passagemeans operatively connecting said servomotor to said first-mentionedvalve means, and an additional shift valve means operatively connectedto said source and to said brake means to supply pressure fluid to saidbrake means to effect release of said brake means in response to theupshift upshifting of said last and second-mentioned shift valves.
 6. Ina transmission having an input and an output, a hydrodynamictorque-transmitting unit having an input rotor operatively connected tosaid input and having an output rotor, a change speed gear unitdrivingly connecting said output rotor and said transmission output,torque-transmitting means drivingly connected to said gear unit,selectively engageable clutch means for drivingly connecting and fordisconnecting said torque-transmitting means and said transmissioninput, hydraulically actuated motor means for operating said clutchmeans, a source of fluid pressure, first feed means operativelyconnected to said source for feeding said hydrodynamic unit, shift valvemeans operatively connected to said source and positionable in a firstposition in response to predetermined torque to route converter feed oilto said motor means to effect disengagement of said clutch and controlvalve means responding to a signal pressure from said shift valve meansby routing fluid from said clutch to exhaust at said shift valve meansto permit hydrodynamic unit pressure to effect engagement of saidclutch.
 7. In a transmission having an input and an output, ahydrodynamic torque converter having a housing with pump meansoperatively connected to said input and having turbine means, a changespeed planetary gear unit having first and second inputs and having anoutput drivingly connected to said transmission output, a plurality offriction drive establishing devices operatively connected to said gearunit which are selectively engageable to produce first, second and thirdinput/output speed ratios, a fluid-operated clutch disposed in saidconverter and engaged by fluid within said converter for drivinglyconnecting said transmission input with said second input of saidgearset, means for supplying fluid to said converter for releasing saidclutch, a source of fluid pressure, a plurality of shift valvesoperatively connected to said source and to said friction driveestablishing devices for shifting said transmission betweenpredetermined input/output speed ratios, an accumulator valve meansoperatively connected to said clutch to control the engagement thereof,said accumulator valve having an accumulator chamber for collecting asignal pressure from said shift valve means and subsequently shifting toroute oil from said converter clutch to said shift valve means and to anexhaust whereby said converter clutch is engaged by working fluid withinsaid converter.
 8. In a transmission having an input and an output, ahydrodynamic torque converter having a housing with pump meansoperatively connected to said input and having turbine means, a changespeed planetary gear unit having first and second inputs and having anoutput drivingly connected to said transmission output, a plurality ofhydraulically actuated friction drive establishing devices operativelyconnected to said gear unit which are selectively engageable to producea plurality of different input/output speed ratios, a fluid-operatedclutch disposed within said converter and engageable by fluid thereinfor drivingly connecting said transmission input with said second inputof said gearset, a source of fluid pressure, shift valve meansresponding to predetermined operating signals of said transmission forrouting operating oil to said clutch within said converter to effect thedisengagement thereof to provide for all hydraulic drive of said gearunit by said converter, control valve means operatively connected tosaid shift valve means and movable in response to a signal pressure fromsaid shift valve means to connect said clutch means with an exhaust insaid shift valve means to effect the rapid exhaust of said clutch andthe engagement of said clutch by working fluid within said converter. 9.In a transmission having an input and an output, a hydrodynamic torqueconverter having pump means driven by said input and having turbinemeans, a planetary gear unit operatively connected to said output,torque transmitting means drivingly connecting said turbine means tosaid planetary gear unit, a plurality of friction drive establishingdevices operatively connected to said gear unit and engageable tocondition said transmission for a plurality of forward driveinput/output gear ratios, said torque converter having a housingconnected to said pump means and driven by said input, clutch meansoperatively disposed in said housing, a torque-transmitting shaftdrivingly connecting said clutch means and said planetary gear unit, aclutch support hub secured to said torque-transmitting shaft, a pressureplate having a friction surface engageable with said housing forming aportion of said clutch means mounted for longitudinal sliding movementon said support, said plate and said housing forming a chamber therein,control means for said transmission including first means for feedingconverter charge fluid to said chamber to effect movement of said platefrom engagement with said housing to effect disengagement of said clutchmeans and the exhaust fluid from said chamber, and including secondmeans for feeding fluid into said converter when said first means isexhausting fluid from said converter so that converter pressure effectsengagement of said clutch means.
 10. The transmission defined in claim 9wherein said controls include a plurality of shifter valves operativelyconnected to said friction drive establishing device and an accumulatorvalve for controlling the engagement of said clutch, said valve havingan accumulator piston which forms a pressure chamber connected with saidshIft valve, said chamber becoming charged with pressure fluid from saidvalve when said shift valve upshifts said accumulator piston operatingon a boost valve to move the regulator valve to a position whereby theconverter clutch line is opened to the two-three accumulator line and isexhausted at shift valve to calibrate the engagement of said clutch. 11.In an automatic transmission having an input and an output, ahydrodynamic unit having an input rotor and having an output rotor, ahousing for said unit driven by said input and drivingly connected tosaid input rotor, change speed gear means drivingly connecting saidoutput rotor to said transmission output, a plurality of friction driveestablishing devices operatively connected to said gear means andselectively engageable for changing the input/output speed ratio of saidtransmission, a clutch in said housing of said hydrodynamic unit, saidclutch having clutch drive means driven by said input, and clutch-drivenmeans drivingly connected to said gear means, a supporting plate formingpart of said driven means and cooperating with said housing to form apressure chamber, control means for said friction drive establishingdevices and said clutch means comprising a source of fluid pressure, aplurality of shift control valve means operatively connected to saidsource and said friction drive establishing devices, torque demand andoutput speed signal means operatively connected to said shifter valvemeans for upshifting and downshifting said valve means, an accumulatorvalve means operatively connected to said source and at least one ofsaid shift valve means, said accumulator valve having regulator meansfor supplying regulated pressure to said chamber to effect disengagementof said clutch means and to feed said hydrodynamic unit, saidaccumulator valve having an accumulator valve element movable to apredetermined position to effect the exhaust of said chamber so thatpressure within said unit will effect the engagement of said clutch. 12.The automatic transmission defined in claim 11, said clutch-driven meanscomprising a supporting hub having an annular shoulder, said supportingplate having a sleeve portion for mounting said plate on said supportingmeans, drive means for drivingly connecting said plate and saidsupporting means while permitting axial movement of said plate, andspring means disposed for urging said clutch drive and driven means intodrive engagement with each other.